System and method for dynamic lubrication adjustment for a lubrication analysis system

ABSTRACT

A system and methodology is provided for dynamically adjusting fluids that operate as a lubricant in a machine. The system includes a control module having a processor and one or more sensors providing data to the processor in situ with the machine, wherein the processor employs the data to monitor the fluid. One or more inputs are provided to receive a plurality of additives that are associated with the fluid, wherein actuators are employed by the processor to dispense the additives to the fluid. The processor dispenses the fluid based upon one or more parameters of the fluid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/370,866, filed Feb. 20, 2003 now U.S. Pat. No. 6,877,360, entitled,“SYSTEM AND METHOD FOR DYNAMIC LUBRICATION ADJUSTMENT FOR A LUBRICATIONANALYSIS SYSTEM,” which is a continuation of U.S. patent applicationSer. No. 10/036,154, filed Oct. 22, 2001, now U.S. Pat. No. 6,546,785,entitled, “SYSTEM AND METHOD FOR DYNAMIC LUBRICATION ADJUSTMENT FOR ALUBRICATION ANALYSIS SYSTEM,” which is a Continuation-in-Part of U.S.patent application Ser. No. 09/257,680, filed Feb. 25, 1999, now U.S.Pat. No. 6,324,899, entitled, “BEARING SENSOR INTEGRATION FOR ALUBRICATION ANALYSIS SYSTEM,” which is a Continuation-in-Part of U.S.patent application Ser. No. 09/054,117, filed Apr. 2, 1998, now U.S.Pat. No. 6,023,961, entitled, “MICRO VISCOSITY SENSOR AND LUBRICATIONANALYSIS SYSTEM EMPLOYING THE SAME.” The entireties of theaforementioned applications are incorporated herein by reference.

TECHNICAL FIELD

The present invention generally relates to a lubrication analysis systemand more particularly to dynamic lubrication adjustment for such asystem.

BACKGROUND OF THE INVENTION

Dynamoelectric machines such as motors and generators are widelyemployed in industrial and commercial facilities. Many facilitiesoperate several hundred or even thousands of such machines concurrentlyand these machines are often integral components of large interdependentprocesses. Accordingly, the machines are each depended upon forprolonged consistent operation whereby it is extremely advantageous toprovide reliable failure prediction information. Of particular relevancein the present invention are bearing-related failures and, moreparticularly, failures related to lubrication problems in antifrictionbearings. Diagnostic studies have consistently reflected thatbearing-related failures are a substantial cause (about 42% of reportedfailures) of motor failures.

An antifriction bearing is designed to constrain rotary or linear motionwhile minimizing wear and other losses such as friction. Examples ofthis type of bearing are sleeve bearings, hydrodynamic bearings, androlling element bearings. The most prevalent bearing type found onmedium and low horsepower (e.g. fractional to 500 hp) motors are rollingelement bearings such as ball bearings. To this end, typicalantifriction bearings normally include a bearing housing defining anannular chamber and a plurality of rolling elements retained within thechamber. The bearing housing typically includes two annular componentsknown as raceways, and more particularly an outer raceway and an innerraceway having interior surfaces which form the radial walls of thebearing chamber. (In the context of the present invention, “interior”corresponds to the relation of the surface relative to the chamber.) Forexample, the outer raceway may be mounted to a machine (e.g., a motor)and is intended to remain stationary relative thereto, while the innerraceway supports a rotating member (e.g., the motor's rotor or shaft).

The rolling elements may be either balls or rollers and the bearing mayinclude one or more rows of such rolling elements. A cage is usuallyprovided to retain the rolling elements in their correct relativepositions so that they do not touch one another and to provide someguidance for the rolling elements. Also a lubricating fluid, such as oilor grease, is contained within the bearing chamber to reduce thefriction between the components and also assist in the dissipation ofheat. The top and bottom (or axial) ends of the chamber are sealed bythe mounting structure or by sealing covers to maintain the lubricatingfluid within the bearing chamber and/or keep dirt or other contaminantsout. An antifriction bearing may include a circulating system to injectand/or drain lubricating fluid into the bearing chamber.

The loss of lubricating effectiveness will result in accelerated wear ofthe bearing elements, additional heat generation due to frictionaleffects, higher levels of vibration and potential impact loading due tometal-to-metal contact, and accelerated degradation of lubricant healthdue to higher levels of temperature, metal particulate contamination,and higher loading/shear levels.

Needless to say, the health of lubrication is a significant factor inthe overall operation of an antifriction bearing. Accordingly, it isessential that the lubrication of an antifriction bearing be properlyprovided, protected, and maintained. Initially, it is important that thecorrect lubricating fluid be provided for the antifriction bearing.Also, it is critical that an adequate amount of lubricating fluid bemaintained in the bearing. Likewise, it is crucial that contaminants(such as water, rust, and other contaminations) not contaminate thelubricating fluid. Moreover, when the lubricating fluid is continuouslyexposed to elevated temperatures, accelerated speeds, high stress/loads,and an oxidizing environment, the lubricating fluid will inevitablydeteriorate and lose its lubricating effectiveness.

Also, when machinery is re-lubricated by applying additional lubricant,the addition of a different, incompatible lubricant will result inconsiderably diminished lubricating effectiveness. The result may beaccelerated bearing wear beyond what would occur if no additional lubewas added. The loss of bearing lubricant due to a seal failure isimportant to detect to prevent accelerated bearing wear and to avoid adry running condition. It is also important to detect the loss ofbearing lubricant in critical manufacturing processes such aspharmaceutical, medical products, and food products manufacturing. Lossof lubricant could result in a contaminated product or worse acontaminated product which remains undetected before reaching theconsumer.

Lubrication-related problems tend to be insidious. There is often only aminor degradation of the lubricating fluid at the beginning. However,continued operation of the machine results in even greater heatgeneration and accelerated degradation of the lubricating fluid. Leftuntreated, the bearing will eventually fail leading to substantialmachinery damage. In short, the continued operation of a degradedbearing will generally destroy machinery beyond just the bearing andrepair costs can be extremely high, not to mention the catastrophic andpotentially unsafe conditions such a failure creates. Unfortunately,many lubrication-related problems are only recognized after irreparabledestruction has occurred to not only the bearing, but the machineitself. For example, some lubricant problems eventually result in abearing seizing up and the continued rotary motion destroying therotating shaft or the bearing mounting. Alternatively uncontrolledvibration could occur, resulting in destruction of machinery andbuildings.

The previous discussion presented bearings and lubrication issues fromthe standpoint of motor-mounted bearings. The problems identified andthe need for lubricant health information applies to bearings found in awide range of machinery, including machinery connected to a motor(driven equipment), land-based vehicles, shipboard systems and aircraftsystems. This includes bearings in internal combustion engines, engineaccessories, gears and gear systems, wheels, linear slides, conveyors,rollers, and pillow blocks for example.

Accordingly, an early diagnosis and cure of lubrication-related problemscan be extremely beneficial in reducing machine down-time, repair cost,inconvenience, and even hazardous situations. For this reason,conservative lubricant changing schedules (where the lubricating fluidis changed well before any degradation is expected to occur) aresometimes well worth what may be viewed as wasted labor and wastedlubricating fluid and un-necessary machinery downtime if needed. Othertimes, however, the cost and labor associated with replacing adequatefunctioning lubricating fluid cannot be justified. Additionally, themore frequent the changes, the higher the possibility that the wronglubricating fluid will be provided and/or other changing mistakes willbe made such as over lubricating equipment. More importantly, eachlubrication situation seems to be relatively unique in view of thealmost countless factors that can contribute to lubrication degradation.As such, in many situations, a lubricating fluid will reach at least theinitial stages of breakdown or contamination well before even aconservative scheduled change.

The potential damage associated with inadequate bearing lubrication andthe uniqueness of each lubrication situation has led many industries toadopt programs of periodic monitoring and analyzing of the lubricatingfluid. In some programs, for example, the condition of the lubricationis determined by measuring a dielectric constant change in thelubricating fluid. In other programs, for example, the condition of thelubrication is instead determined by recording historical thermalreadings. Unfortunately, these programs measure only a single parameter,such as temperature over time, require the use of the same lubricatingfluid, and/or assume no machinery malfunctions between measurements.Furthermore, extensive lubrication monitoring and analysis techniquesare not performed in situ and typically involve extracting a sample ofthe lubricating fluid and then analyzing this sample using laboratoryequipment. As such, these sampling techniques only provide a narrow,periodic view of lubrication quality and/or health whereby accuratelubrication health assessment and lifetime prediction is virtuallyimpossible to achieve. Moreover, the manpower required to extract thelubricant samples necessarily limits the frequency of sampling, not tomention the introduction of human error into the extraction process. Insome situations, lubricating oil may be extracted from machinery and putin glass bottles in front of a light source. A visual inspection is madeafter the material had settled.

In view of the above, analysis of fluids including lubricating fluids isan extremely important area and rapidly growing in importance (e.g.,machinery, safety, environmental, and so forth). There is a significantexpenditure of dollars for outside lab analysis of fluids and also forstaff time and for on-site factory-resident labs. Also, there are avariety of lube analysis techniques that include lab analysis methods(e.g., titration methods) and sensor-based methods (e.g., pH sensors,H₂O sensors, dielectric sensors). Lab analysis techniques, however, arelimited due to the time delay before a lube analysis is available,possible contamination of the samples extracted for analysis, the costrequired for the analysis, and the difficulty in determining whatcorrective action is needed and when.

Although lube sensors offer improvement over how machines weremaintained in the past, other problems are still encountered. Forexample, maintenance engineers generally still must go to the machineryand lubricate equipment periodically based on equipment usage andlubrication health. In addition, many pieces of rotating machinery andassociated grease fittings are difficult to reach, whereby otherproblems relate to accelerated failure due to over lubricating equipmentand by employing the wrong type of lubrication, for example.

SUMMARY OF THE INVENTION

The following presents a simplified summary of the invention in order toprovide a basic understanding of some aspects of the invention. Thissummary is not an extensive overview of the invention. It is intended toneither identify key or critical elements of the invention nor delineatethe scope of the invention. Its sole purpose is to present some conceptsof the invention in a simplified form as a prelude to the more detaileddescription that is presented later.

The present invention relates to a system and methodology to facilitateanalysis, diagnosis and maintenance of lubricating fluids and tomitigate costs associated therewith. A low-cost fluid sensor forembedded applications can be applied to a plurality of diverseapplications and can be employed to dynamically control quantitative andqualitative aspects of the fluids in order to mitigate effects such asdegradation, depletion, and oxidation, for example. As an example of thediversity provided by the present invention, embedded applications caninclude automotive (e.g., engine, drive train, cooling systems, fuels),industrial machinery (e.g., gears, bearings, cutting fluids, hydraulicfluids), aircraft, food processing (e.g., oils, preservatives), andmedical (e.g., in-vivo applications, medicines, other bio-fluids).

In accordance with one aspect of the present invention, amultifunctional and modular system is provided that includes one or moresensors to monitor fluids such as lubricants, hydraulics, oils andgreases, for example. Information received by the sensors is thenprocessed to determine if the fluids are functioning according topredetermined ranges of suitable fluid operating parameters. If it isdetermined that one or more parameters are outside of the predeterminedoperating ranges, one or more actuators or valves are provided that candynamically adjust one or more of the fluid parameters—even duringoperation of related machinery or other equipment.

Dynamic adjustments to fluids can include adjusting fluid levels andchemical deficiencies in the fluids along with adjusting characteristicsof the fluid based upon environmental considerations (e.g., making fluidadjustments according to duty cycle, load, and temperature of associatedequipment). The sensor information can also be provided to externalcontrol systems to adjust operating characteristics in accordance withthe current detected state of the fluids. For example, if a fluid weredetermined to be running hotter because of depletion, the sensorinformation can be employed to adjust the speed or torque of acontroller and related equipment in order to extend the life of thelubricant.

Another aspect of the present invention includes utilizing the sensorinformation collected above to further enhance diagnostic and prognosticaspects of the present invention. This can include providing dataquality metrics along with sensor information to indicate not only theoperating characteristics of fluids but also to indicate informationthat relates to the health or status of the sensor reporting the fluidinformation. In this manner, equipment can be better maintained sinceinformation is provided according to the current operating status of thefluids indicating when corrective actions are needed. To furtherfacilitate the process, predictive information is provided relating tothe quality of the components that detect when the corrective actionsare needed, thus increasing the overall confidence and accuracy of thesystem.

According to another aspect of the present invention, lubricantoperating life is extended to further reduce maintenance and costsassociated with lubricant replacement. This can be achieved by excitingone or more electrodes via excitation pulses to reduce oxidation presentin the lubricants. In addition, other processes can include energizingone or more magnetic or other type structures to facilitate removal ofmetallic particles that may have accumulated in the lubricant—thus,enhancing operational life of the lubricant. By reducing oxidation andcontaminants in the lubricant, effective lubricant lifetime can beextended. Thus, the period required for re-lubricating equipment can beextended and possibly, a lubrication cycle can be eliminated.Consequently, maintenance costs and equipment downtime can be mitigated.Costs can also be saved by deferring re-lubrication until a future plantshutdown and/or scheduled downtime due to the extended life of thelubricant.

Sampling and subsequent restorative operations provided to lubricantscan occur as an on-going process, in real time and as part of a closedloop process. Thus, the present invention can incorporate amulti-element lubrication health sensor along with processing andcontrol aspects to not only determine but also to change or affect theoverall health of lubricants. Sensors can be implemented in accordancewith the present invention for in situ sensing of lubricating fluidssuch as greases and oils among other fluids, wherein the parameterssensed such as ferrous contamination and oxidation include severalcritical and prevalent parameters indicating lubrication health.Consequently, the health of lubricants can be characterized in order toindicate remaining lubrication lifetime—in order to specify and controlwhen (in the future) bearings, gear boxes, and/or other systems need tobe re-lubricated. Maintenance engineers can then be directed to performthe system maintenance within prescribed times and in some cases lessoften. This facilitates having the engineer move from a preventivemaintenance strategy (e.g., lubricate equipment based on a timedschedule) to a predictive maintenance strategy (e.g., only lubricateequipment when needed to minimize operating costs and extend equipmentlifetime), wherein the control aspects of the present invention furthermitigate maintenance efforts by automatically sensing and subsequentlyoperating upon lubricant characteristics.

The following description and the annexed drawings set forth in detailcertain illustrative aspects of the invention. These aspects areindicative, however, of but a few of the various ways in which theprinciples of the invention may be employed and the present invention isintended to include all such aspects and their equivalents. Otheradvantages and novel features of the invention will become apparent fromthe following detailed description of the invention when considered inconjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary lubrication sensing devicewhich may be used in a bearing-sensor integration according to thepresent invention.

FIG. 2 is an exemplary environment for the bearing-sensor integrationaccording to the present invention is schematically shown.

FIG. 3 is a block diagram showing the interaction of the lubricationsensing device and a lubrication analyzer.

FIGS. 4 a, 4 b and 5–15 are schematic illustrations of variousbearing-sensor integrations according to the present invention.

FIG. 16 is schematic block diagram of a closed-loop module to adjustfluid parameters according to an aspect of the present invention.

FIG. 17 is a flow diagram of a sensor data and quality collection andreporting process according to an aspect of the present invention.

FIG. 18 is schematic block diagram of a closed-loop module to adjustfluid characteristics according to an aspect of the present invention.

FIG. 19 is a flow diagram of a lubrication control process according toan aspect of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to the drawings in detail, and initially to FIG. 1, anexemplary lubrication sensing device 20 is shown in perspective view.According to the present invention, the lubrication sensing device 20 isintegrated into a bearing 22 (FIGS. 4 a, 4 b and 5–13). Thisbearing-sensor integration allows in situ lubrication readings to beobtained at a substantially high data sampling rate whereby accurateup-to-date, real-time, continuous data analysis of lubrication healthmay be provided. In this manner, lubrication maintenance can bescheduled to correspond with the state of the lubrication and/or theprocessed data can be compiled for trend analysis and forecasting.Lubrication maintenance may be reliably scheduled based on the projectedfuture state of the bearing lubricant. Performing maintenance based onprojected future state of the lubricant enables industries to implementeffective condition based maintenance programs.

Although the present invention is primarily described in the context ofball bearing systems, it is to be appreciated that the present inventionapplies to substantially all rolling element bearings (e.g., rollerbearings, cylindrical bearings, taper roller bearings, double row ballbearings, sleeve bearings, hydrodynamic bearings). The scope of thepresent invention as defined by the hereto appended claims is intendedto include such bearing applications.

The illustrated lubrication sensing device 20 may be made in accordancewith integrated circuit-like fabrication techniques thereby making itpossible for the device 20 to have a relatively small geometry, such asa substantially flat square shape having an approximately 4 mm² area orsmaller. Thus, the lubrication sensing device 20 is desirable forbearing-sensor integrations wherein space is at a premium but accuracy,reliability, and sensitivity of measured data are equally as important.Furthermore, the integrated circuit-like fabrication procedures allowthe efficient and economic manufacture of large batches and/or highproduction yields.

The illustrated lubrication sensing device 20 includes a semiconductorbase 24, made of silicon or any other suitable material, and a pluralityof sensors formed on the base 24. The illustrated sensors include a pHsensor 30 (to determine ionic conditions); a chemical sensor 36 (todetermine the presence of chemical contaminants); an electricalconductivity sensor 40 (to determine the presence of metal/watercontaminants); and a temperature sensor or detector 44 (to determinetemperature and facilitate determining viscosity). The pH sensor 30includes a reference electrode 50 and a pH electrode 52. The chemicalsensor 36 includes a reference electrode 54, a working electrode 56, anda counter electrode 58. The conductivity sensor 40 includes two metalelectrodes 40 a and 40 b. The temperature sensor or detector 44 isessentially a pattern (having known geometric dimensions) formed on thebase 24 from a material having an electrical conductivity that varieswithin the expected range of temperatures. The lubrication sensingdevice 20 further comprises respective sets of contact pads 60 a–60 icoupled to the sensors 30, 36, 40 and 44.

Depending on the particular bearing-sensor integration, the illustratedlubrication sensing device 20 may be acceptable and even preferable.However, other lubrication sensing devices are possible with andcontemplated by the present invention, and may be more advantageous incertain bearing-sensor integration situations. For example, depending onthe desired data collection, certain sensors may be omitted, certainsensors may be repeated, the sensitivities of replicated sensors sealedto cover a wide dynamic range, and/or different types of sensors may beadded. For a specific example, a viscosity sensor may be provided thatworks in conjunction with the temperature sensor 44 to measure thelubricant's viscosity. (A suitable viscosity sensor is shown anddescribed in U.S. Pat. No. 6,023,961, entitled, “MICRO-VISCOSITY SENSORAND LUBRICATION ANALYSIS SYSTEM EMPLOYING THE SAME.”)

Additionally or alternatively, instead of the rigid silicon substratebase 24, the sensors 30, 36, 40 and 44 could be fabricated on a flexiblesubstrate material to accommodate, for instance, in connection with thebearing-sensor integrations shown in FIGS. 4–7. Also, the sensors 30,36, 40, and 44, could be located on both sides of the rigid or flexiblesubstrate base 24 as might be desirable in, for instance, in thebearing-sensor integration shown in FIG. 9. Alternatively, the sensors30, 36, 40, and 44 could be “printed” on the bearing 22 itself (e.g.,using techniques such as sputtering) to eliminate the need for thesubstrate 24 as may be advantageous in, for instance, the bearing-sensorintegrations shown in FIGS. 4–8. Moreover, as is discussed in moredetail below, a processing unit may be incorporated into the lubricationsensing device 20 to perform data acquisition, analyzer functions,communications, afford self diagnosis, establish lubricant health,predict when lubricant service is required, and/or verify feasibleoperating regimes.

Referring now additionally to FIG. 2, an exemplary environment for thebearing-sensor integration according to the present invention isschematically shown. In the illustrated example, a lubrication analysissystem 68 is used in conjunction with a motor 70. The illustrated motor70 may be a three-phase AC induction motor that drives a load 72 througha shaft coupling 74 and a junction box 76 is provided to receive and tiepower supply lines. In any event, the motor 70 includes one (andprobably more) antifriction bearings. For example, two antifrictionbearings would typically be used to mount the motor's rotor and/or shaft74 to the motor end brackets. The system 68 measures, determines,analyzes, monitors, and/or controls the lubrication health of thebearing based on readings received from one or more lubrication sensingdevices 20 embedded in the bearings.

The lubrication analysis system 68 includes an analyzer 90 which, in theillustrated embodiment includes a display 92 for displayinglubrication-related information and a keypad 98 for entering data and/orcommands. The system 68 further comprises a host computer 102 that makesdeterminations as to the health of the lubrication, this determinationpreferably including performing data fusion of the sensed lubricant data(e.g., pH, chemical, conductivity, temperature) to facilitatecondensing, combining, trending, forecasting, evaluating andinterpreting the sensed data. The analyzer 90 includes a communicationsport 106 or other interface for receiving information from thelubrication sensing device(s) 20. Once the analyzer 90 (and moreparticularly its processor 130, introduced below) has processed thelubrication-related data, it is sent to the host computer 102 via anetwork backbone 120 (which may be hardwired and/or wireless). In thismanner, the highly accurate and up-to-date information may be providedregarding the health of the lubrication. Data may be combined frommultiple bearings in the host computer 102 and lubrication health andfuture lubrication requirements may be communicated to plantmaintenance, job scheduling, routing, and inventory systems asappropriate.

Referring now to FIG. 3, further details of the analyzer 90, and itsinformational connection to the lubrication sensing device 20, areschematically shown. The lubrication analyzer 90 includes a processor130 which analyzes information received from the lubrication sensingdevice 20. To this end, the pH sensor 30, the chemical sensor 36, andthe conductivity sensor 40 are directly coupled to A/D converters 136_(pH), 136 _(chem), and 136 _(cond), respectively. The temperaturesensor (or detector) 44 is coupled to the A/D converter 136 _(temp)through a voltage sensor 134. The sensors 30, 36, 40, and 44 are eachoperatively coupled to the processor 130 via respective A/D converters136.

The lubrication analyzer 90 includes a memory 164 that stores programcode, base-line information (e.g., nominal temperature, acceptable pH,expected electrochemistry, re-lube information, loading information,duty cycle data, and appropriate viscosity values), machine specificdata, acceptable error bounds/deviations, historical lubricant parameterdata, and/or recommended corrective action. The lubrication analyzer 90may also include a power supply 170 (that provides power to theprocessor 130, sensors and other components), a display driver circuit180 (that couples the processor to the display 92), RF section 190 (thatincludes a receiver 192, an antenna 194, a transmitter 196 thattransmits and receives signals), a voltage driver 197 (that provides thedesired voltage to the lubrication sensing device 20), and/or anadaptive processor 198 (that analyzes the health state of thelubrication).

The lubrication analysis system 68 is designed to provide highlyaccurate and up-to-date information regarding the health of thelubrication. Additionally, this system will compare known lubricanthealth with acceptable parameters and projected lubricant aging toestablish a recommended maintenance action and when this maintenancemust be performed. This information is then communicated to an operatoror other computer system as appropriate. Depending on the particularanalysis situation and/or the specific bearing-sensor integration, theabove-described lubrication analysis system 68 may be acceptable andeven advantageous in certain situations. However, other lubricationanalysis systems are possible with and contemplated by the presentinvention, and may even be preferable in certain bearing-sensorintegrations according to the present invention.

For example, all of the processing functions (data analysis, lubricantstate estimation, health determination, etc.) performed by the hostcomputer 102 in the illustrated embodiment could instead by performed bythe processor 130 of the lubrication analyzer 90. In this arrangement,the processed results could be transmitted to a portable computertemporarily tied to the lubrication analyzer 90 and/or transmitted to aremote control computer. Additionally or alternatively, the processedresults could be displayed locally on the analyzer display screen 92.

For another example, the lubrication analyzer 90 could be locatedremotely from the motor 70 or the host computer 102 could carry outsubstantially all of the lubrication analyzer functions performed by theprocessor 130 in the illustrated system 68. Another option is tointegrate the lubrication analyzer 90 (absent certain components, suchas the display 92 and the keypad 98) onto the same base 24 as thelubrication sensing device 20 and/or the bearing 22 to provide for asubstantially autonomous lubrication analysis system that performsanalyzer functions, affords self diagnosis, and verifies feasibleoperating regimes.

For a further example, the transmittal of the readings by the sensors30, 36, 40, and 44 could be modified to fit a particular bearing-sensorintegration. In the illustrated lubrication analysis system 68, theanalyzer 90 includes the communications port 106 or other interface forreceiving information from the lubrication sensing device(s) 20.However, with certain bearing-sensor integrations, such as those shownin FIGS. 6 and 7, wireless sensor technology may be preferred.Additionally or alternatively, in certain bearing-sensor integrations,such as that shown in FIG. 7, an intercommunication between sensors 20(certain sensing devices 20 relaying information to other sensingdevices which then transmit the relayed information to the lubricationanalyzer 90) may be the preferred transmittal procedure. To accomplishthis wireless technology, low cost integrated silicon RF technology maybe coupled to the on-board processor 130. As a further improvement, amagnetic field may be attached to a rotating component of the bearing 22(such as its inner raceway 210, introduced below), to make thelubrication sensing device 20 self-powering.

For a still further example, the lubrication analysis system 68 couldadditionally initiate automatic correction procedures. For instance, ifthe bearing 22 includes a forced lubrication system (such as the system220 introduced below and shown schematically in FIG. 10), the injectionor draining of lubricating fluid could be automatically controlled basedon the current lubrication health analysis. Specifically, the detectionof low levels of lubricant could automatically trigger the injection offresh lubricant until an adequate level is reached. The presence of anunacceptable amount of contaminants could trigger a flushing oflubricant to decontaminate the bearing environment. Additionally oralternatively, additives (such as anti-oxidant/desiccant substances)could be automatically introduced to stabilize lubrication performanceor even to provide survival lubrication performance during conditions ofextreme wear, temperature, duty or mission critical applications.Automatic monitoring and subsequent correction of fluids and otheraspects of the present invention are further described in accordancewith FIGS. 16 through 19 that are described in more detail below.

By introducing prescribed amounts of additives, lubricant healthassessment may be enhanced by monitoring the rate of degradation of thenew material. It is also noted that while the lubrication analyzer 90preferably performs a plurality of functions relating to lubricationhealth, the processor 130 could be employed for the sole purpose ofdoing an emergency shut-down of the motor 70 when lubrication conditionsapproach a critical level.

Referring now to FIGS. 4–15, various bearing-sensor integrationsaccording to the present invention are schematically shown. The bearing22 is a ball bearing roller bearing of a conventional design and may beviewed as comprising a housing 202 defining a chamber 204 and aplurality of rolling elements 206 (ball bearings in the illustratedembodiment) within the chamber 204. The bearing housing 202 includes anouter raceway 208 and an inner raceway 210 having interior surfaceswhich form the radial walls of the annular chamber 204. (In the contextof the present invention, “interior” corresponds to the relation of thesurface relative to the chamber 204.) In the illustrated embodiment, theouter raceway 208 is mounted to the machine (e.g., the motor 70 endbracket) and is intended to remain stationary relative thereto, whilethe inner raceway 210 supports a rotating member (e.g., the shaft 74).Note, the stationary and rotating elements may be reversed withoutaltering the application of the proposed concept. That is, the innerrace may be fixed and the outer race may rotate, for example, astypically occurs in an automobile front wheel bearing.

The bearing 22 further includes a cage 212 to retain the rollingelements 206 in their correct relative positions within the chamber 204and to provide some guidance during the rotation of the inner raceway210. Also, a lubricating fluid 214, such as oil or grease, is containedwithin the bearing chamber 204 to reduce the friction between thecomponents and also assist in the dissipation of heat. The top andbottom (or axial) ends of the chamber 204 are sealed by sealing covers(e.g. bearing seals, bearing shields, or the bearing mounting structure)216 to maintain the lubricating fluid 214 within the bearing chamber204. (FIG. 9.) The sealing covers 216 may be, for example, washer-shapedmembers made of felt, leather, plastic, metal, or other suitablematerials to seal the annular space between the adjacent axial surfacesof the outer raceway 208 and the inner raceway 210.

The bearing 22 may include an inlet pipe 224 through which freshlubricating fluid or additive is pumped into the bearing chamber 204.(FIG. 10.) The inlet pipe 224 may be attached to a pump or pressurizedvessel which automatically introduces fresh lubrication fluid 214 intothe chamber 204 and an outlet pipe 206 may be provided to automaticallydrain the lubricating fluid 214 therefrom. (FIG. 10.) The introductionof fresh lube or additive is performed using a small activatorintegrated with the lube analyzer system. Alternatively, the inlet pipe224 may be plugged at one end with, for instance, a threaded cap 228(FIGS. 11 and 12) which may removed for introduction of freshlubrication fluid. As another alternative, the sensor may be integratedwith the grease and/or drain fitting used in conventional re-lubricatedbearing systems.

Referring now particularly to FIGS. 4 a and 4 b, one bearing-sensorintegration according to the present invention is shown. In thisembodiment, the lubrication sensing device 20 is mounted on an interiorsurface of the outer raceway 208. Preferably, a small area (about 1 to 4mm²) is machined in the inner surface of the raceway 208 to provide amounting location for the sensor 20. The mounting location is preferablyin close proximity to the center circular contact path of the ballbearings 206 on the outer raceway 208, but slightly off-center relativethereto to avoid direct contact. Preferably, a wiper arm 240 (such asminiature windshield wiper) has one end pivotally attached to thebearing 22 (and particularly the cage 212) whereby as the cage 212rotates, unattached portions of the wiper arm 240 are pivoted totransport a changing wedge of the lubricating fluid 214 around the outerraceway 208 and across the sensor 20. It is to be appreciated that aparticular embodiment of the invention may have 0 to N (N being aninteger) number of wipers. If the analyzer 90 (particularly itsprocessor 130) is incorporated into the lubrication sensing device 20and/or the bearing 22, this incorporation will provide for asubstantially autonomous lubrication analysis system. Also, thenon-sensor components (electronics, filtering, processing, and/orcommunications elements) may be located on the exterior surface of theouter raceway 208 and with vias or solderable contact points extendingthrough the outer raceway 208.

Referring to FIG. 5, a plurality of lubrication sensing devices 20 aremounted on an inner surface of the outer raceway 208. Each of thedevices 20 may be mounted in the same manner as the single lubricationsensing device 20 described above in connection with FIG. 4 a.Preferably, the sensing devices 20 are equally spaced around thecircumference of the outer raceway 208, such as between each rollingelement 206. In any event, the use of multiple sensing devices 20improves analytical accuracy by expanding the range/location of sensorreadings, enhances system reliability by redundancy, permitsself-diagnosis of the sensors (e.g., a faulty sensor is easily noticedwhen compared to its sister sensors), allows the correlation of multiplesensor readings over time (to determine, for example, fluid transporttime), and essentially guarantees that different samples of thelubricating fluid 214 are being sensed at least by different sensors.From an economic standpoint, the increased expense of a multiple vs.single lubrication sensing device set-up is approximately equal to thecost of the extra sensing devices per se, since shared processing and/orcommunication for multiple sensing devices is possible.

Referring to FIG. 6, a plurality of lubrication sensing devices 20 aremounted on an inner surface of the inner raceway 210. As was explainedabove, in the illustrated bearing 22, the outer raceway 208 isstationary and the inner raceway 210 rotates during operation of themachine. Accordingly, positioning the sensing devices 20 on the innerrotating raceway 210, as compared to the outer non-rotating raceway 208,may permit a faster sampling of the lubricating fluid 214 and overconditions of changing loading. Preferably wireless sensor technology isused to convey information from the sensors for processing so as toavoid having to run electrical connections from the inner raceway 210 tooutside the bearing. (Since the exterior surface of the inner raceway210 is attached to, for example, the rotating shaft 74, such anelectrical connection would require the use of slip-rings if wirelesstechnology was not employed.) Alternatively, the sensing devices 20mounted on the inner raceway 210 could communicate to other sensingdevices within the bearing 22 to permit realtime, continuous monitoringof the elastohydrodynamic film produced by the lubricating fluid 214.

Referring now to FIG. 7, a plurality of lubrication sensing devices 20are mounted on both the outer raceway 208 and the inner raceway 210.This arrangement would allow the sensing devices 20 on the inner raceway210 to communicate to the sensing devices 20 on the outer raceway 208.Additionally or alternatively, this arrangement allows the measurementof the electrical and thermal potential between the outer raceway 208and the inner raceway 210 thereby providing an indication of bearing andlubricant film conductivity and/or the presence of bearing currents.

Referring now to FIG. 8, the lubrication sensing device 20 is mounted onthe cage 212 of the bearing 22. Mounting the sensing device 20 (or atleast the sensors) on the “ball-side” of the cage 212, positions thesensors, in a controlled manner, very close to a moving film of changinglubricant near the surface of the rolling element 206. However, mountingof the sensing device 20 “outside-the ball” side of the cage 212 (asshown) still exposes the sensors to different lubricant locations as thecage 212 traverses around the inner raceway 210 while at the same timeminimizing the risk of contact with the adjacent rolling element 206.

Referring now to FIG. 9, the lubrication sensing device 20 is located onthe sealing cover 216 of the bearing 22. The sensing device 20 may beattached to a conventional cover or may be incorporated into the coverduring its manufacture. In either event, such an arrangement providesfor simplified installation and/or replacement of the lubricationsensing device 20. Specifically, an old sealing cover may be removed(usually a relatively inexpensive component as compared to the othercomponents of the bearing, such as the housing 202, the rolling elements206, and/or the cage 212), and the sealing cover 216 including thelubrication sensing device 20 installed. Also, the lubrication sensingdevice 20 may be designed (or the sealing cover 216 may includeadditional instrumentation) to detect and pinpoint lubrication-relatedproblems such as lubrication leakage and/or improperly installed orseated sealing covers. For example, a double-sided sensing device 20could have sensors on its interior surface to sense pH, chemicalconditions, conductivity, temperature and/or viscosity and sensors onits exterior surface for detecting lubricant leakage.

Referring to FIG. 10, the lubrication sensing device 20 may bepositioned within the outlet pipe 226 of the circulating system 220.This bearing-sensor integration allows the incorporation of alubrication analysis system by simplifying re-plumbing the circulationpipes thereby leaving the bearing 22 intact. For similar reasons, thisbearing-sensor integration simplifies manufacture, installation, testingand field maintenance procedures of the lubrication sensing device(s)20. Another significant advantage of this embodiment of the invention isthe convenience of operably tying the processed sensor data to thecirculation control. Specifically, if the processed sensor data reflectsthat the lubricating fluid 214 is acceptable, the sample of lubricatingfluid 214 may flow back through a bypass pipe (not shown) and introducedback into the bearing chamber 204. However, if the processed sensor datareveals that the lubricating fluid 214 is degraded, the bypass may beclosed and the pump activated to inject fresh lubricating fluid into thebearing chamber 204 through the inlet pipe 224 until acceptable sensorreadings are received. Alternatively, only additives may be introducedinto the lube to accommodate depleted additives (such as anti-oxidants)and re-establish proper lube chemistry.

Referring now to FIGS. 11 and 12, the lubrication sensing device 20 ismounted to a cap 228. In the cap-sensor integration shown in FIG. 11,the sensing device 20 is attached directly to the cap 228. In thecap-sensor integration shown in FIG. 12, the sensing device 20 isattached to a probe 242 extending through the cap 228. In either event,such a cap-sensor incorporation provides for simplified installation ofthe lubrication sensing device 20 by removal of the conventional capand/or probe and replacement thereof by one including the sensing device20. Such a cap-sensor integration may be employed in many types ofmachines employing lubrication and/or fluid reservoirs.

Referring now to FIG. 13, the lubrication sensing device 20 may bemounted on a compliant structure 244 (conceptually like a “rubberpoliceman”) that is geometrically designed to “ride” a moving filmsurface of lubricant. In this manner, the sensing device 20 (or at leastits sensors) may be positioned in close proximity to the movinglubricant film surface (such as adjacent the raceway 208/210 or the cage212) while at the same time shielding the sensors from direct contactdamage. Also, such a bearing-sensor integration allows the distancing ofnon-sensor electronic elements away from the sensor elements (such aswithin the compliant structure 244 or within the rigid mounting base).

Referring now to FIG. 14, the lubrication sensing device 20 is locatedwithin a flowgate 248. The flowgate 248 defines a small bypass channelfor diverting a small test or sample amount of lubricating fluid 214away from the bearing chamber 204 and then reintroducing it back intothe bearing chamber 204 once it has flowed past the lubrication sensingdevice 20. The flowgate 248 is positioned to utilize the moving actionof the rolling elements 206 and/or the cage 212 to in effect pump asample of the lubricating fluid 214 through the bypass channel. Thisarrangement allows the sensing device 20 be positioned away from themoving components of the bearing 22 (e.g., the rolling elements 206 andthe cage 212) while at the same time providing for a continuous exchangeof lubricant flowing past the sensing device 20. The bypass channel maybe much smaller than shown in FIG. 14 and effectively integrated withinthe outer race 208 of the bearing.

Referring now to FIG. 15, the lubrication sensing device 20 is locatedwithin a small reservoir 252 which communicates with, but is positionedoutside, the bearing chamber 204. A rotating paddle 256 (essentially aminiature paddlewheel or propeller having a hub rotatably mounted to thebearing and paddles projecting radially outward from the hub) isprovided so that it spins as the rolling elements 206 and the cage 212rotate thereby and/or as the lubricating fluid 214 is circulatedthereby. In this manner, the sensing device 20 is constantly presentedwith untested samples of the lubricating fluid 214 while at the sametime the sensing device 20 is physically isolated from the movingbearing components. This bearing-sensor integration may allow a more“rugged” mounting of the sensing device 20, a more precise positioningof the device 20 in relation to the moving lubricating fluid, easierintegration of sensing and electronics components, a mechanical base forself-powered operation, and/or simplified integration of the sensor 20into the bearing 22.

In connection with the bearing-sensor integrations shown in FIGS. 4–15(and also in connection with any other bearing-sensor integrationspossible with and contemplated by the present invention), thereliability and credibility of the processed results depends initiallyon the sensor readings accurately reflecting the true state of thelubricating fluid 214. Specifically, if the sensors are repeatedlysensing the parameters of only a small static portion of the lubricatingfluid 214, rather than the lubricating fluid as a whole, the mostadvanced and sophisticated processing procedures may not be able toprovide an accurate analysis. For this reason, it may be important thatuntested samples of the lubricating fluid 214 be continuouslyencountered by the sensing device(s) 20. In certain bearing-sensorintegrations, this is accomplished by the use of a plurality of sensingdevices 20 (see, e.g., FIGS. 5–7), the positioning of the sensingdevice(s) 20 on or near a moving component of the bearing 22 (see e.g.,FIGS. 6–8), and/or the positioning of the sensing device(s) in locationsof force fluid flow (see e.g., FIGS. 10–13).

In addition to the positioning of the sensing device(s), the use ofcertain supplementary fluid transporting mechanisms may be necessary ordesirable. For example, the wiper arm 240 in the bearing-sensorintegration shown in FIG. 4 a or the paddle 256 in the bearing-sensorintegration shown in FIG. 15, may be used to insure that the sensingdevice(s) 20 are continuously exposed to dynamic samples of thelubricating fluid 214. These transport mechanisms may be duplicated,modified, and/or combined for use in other bearing-sensor integrations.Additionally or alternatively, other actuators may be used to transportuntested lubricant over the sensing elements. For example, an array ofcilia-like coordinated actuators mounted within the bearing 22 mayprovide the necessary or desired transport arrangement. Otherappropriate transport devices include MEMs valves, pumps, andmicro-fluidic devices that could be integrated with the sensing devices20.

One may now appreciate that the present invention provides anintegration of the lubrication sensing device 20 into the bearing 22 sothat a substantially high data sampling rate can be obtained and highlyaccurate, real-time, continuous up-to-date data analysis of lubricationhealth may be provided. In this manner, lubrication maintenance can bescheduled to correspond precisely with the state of the lubricationand/or the processed data can be compiled for trend analysis andforecasting. The time-based expected rate of lube degradation can beused to predict when re-lubrication or other related maintenance action(e.g. replace worn seals) is required. This provides a solid basis forreliable condition-based maintenance directed at one of the mostcritical, high-maintenance, and failure-prone components in rotatingmachinery.

FIG. 16 illustrates a closed-loop system 300 to dynamically adjust fluidparameters according to an aspect of the present invention. The system300 can be included as part of a lubrication sensor, device or sensorarray described above and can be packaged in a control module 310 (e.g.,micro-electronic substrate, PCB, Micro Electrical/Mechanical Machine(MEM) structure), wherein a self-contained electrical power source 312(e.g., battery, piezoelectric power) provides power to components thatare contained within the module 310. It is noted that the power source312 can also be supplied from a source (not shown) external to thecontrol module 310. The control module 310 samples a fluid 316 such aslubricating fluid, hydraulic fluid, oil, grease, fuels, and/or othertype compounds, for example, via one or more sample inputs 320 that aresensed by sensing components 324 (e.g., temperature, pressure,viscosity, chemical and so forth) operatively coupled to a processor andmemory unit 330. It is also noted that the processing and memory unit330 can be provided externally from the control unit 310.

The processing and memory unit 330 can be adapted to monitor thechemistry of the lubricating fluid 316 via the sensing components 324and determine whether additives have been depleted from the fluids suchas anti-oxidants. This can be achieved by setting predeterminedoperating ranges for measured fluid parameter values within the memoryportion of the processing unit 330. If a fluid parameter is out of thepredetermined range of desired fluid performance as reported by thesensing components 324, the processing unit 330 can dynamically adjustthe fluid 316 in accordance with the desired operating range. Forexample, employing small electrical actuators or MEMs valves 334, theprocessing unit 330 permits the introduction of additional fluid, suchas a lubricant, into an operating device (not shown) that is operativewith the fluid 316 to automatically remedy a low lube condition or achemically depleted lubricant. The additional fluid or agent is providedto the control module 310 through additive inputs one though N (340),wherein N is an integer and dispensed via the actuators 334 asdetermined by the processing unit 330. In this manner, a closed loopsystem is provided to maintain the fluid 316 and mitigate costsassociated therewith.

The control module 310 can selectively cause specific chemicals to beintroduced into the fluid 316 via the actuators 334 and additive inputs340 to remedy one or more chemical deficiencies (e.g., pH, viscosity).Alternatively, the control module 310 can selectively cause thechemistry of the fluid 316 to change in response to changing environmentand duty requirements such as a determined or sensed need for hightemperature operation, low temperature operation, and/or heavy loadconditions. The additive inputs 340 can include a “tag” or “marker” topermit early detection of a breakdown of a particular chemical and/orpresence of a particular contaminant and to facilitate detection via thesensing components 324.

Additives can be formulated to permit real-time replenishment and/orrefurbishment of the additives. For example, detergents and otherchemical additives can be introduced to the fluid 316 to enableequipment with deteriorated fluid such as a lubricant to survive for atime without a catastrophic failure. In addition to determining andcontrolling various parameters of the fluid 316, the control module 310can include a bar graph or other type display 344 driven by theprocessing unit 330. The display 344 can report such aspects fluidhealth, remaining lifetime of the fluid before a fluid change is needed,and/or time indications before a filter change is needed, for example.

Other components can also be incorporated within the control module 310.For example, piezoelectric devices (not shown) can be integrated oradditional MEMs components added to permit vibration measurements, ifdesired. Piezoelectric components can also be employed to measureviscosity or density by utilizing structures that are immersed in thefluid 316. Alternatively, piezoelectric components can be employed togenerate power 312 for the control module 310. It is to be appreciatedthat other sensing modalities can also be integrated within the controlmodule 310 such as acoustic wave, magnetic fields with capacitancesensors, optical particle counters and/or optical particle analyzers tofurther sense or detect the health of the fluid 306. It is noted thatthe control module 310 can employ sensor fusion to infer and/ordetermine fluid parameters or other fluid quantities that may not bedirectly measurable (e.g., inferring ph, viscosity or other fluidparameter from the manner in which fluid responds to control moduleoutput or stimulus rather than directly measuring the parameter).

According to another aspect of the present invention, control moduleinformation (e.g., sensor data, fluid parameters, range data) can besent to a control output 350 in order to facilitate dynamic adjustmentsand control of related machinery. For example, if bearing lube isdepleted and running hot, the control output 350 can be operativelycoupled to an external controller (not shown) to limit the maximum speedor torque to a lower level which can extend the useful life of the lubebefore mechanically damaging bearings, gears, or seals. In the case ofair conditioning systems as another example, maximum compressor speed orcompressor pressure can be limited to reduce the rate of freondegradation and/or freon leakage via the control output 350.

It is noted that a control model (not shown) can be employed (e.g., loopclosure around model rather than predetermined parameters describedabove) that projects and/or predicts the impact of various systemchanges according to the overall operating environment or otherconsideration (e.g., load, temperature, power cycling of machine). Forexample, the model can be configured to predict when a lubricant orfluid should be changed according to sensed and/or inferred conditionsof the machinery that utilizes the fluid. It is also noted that themodel can be automatically and adaptively updated or enhanced by thecontrol module in order to refine and better predict future conditionsfor the fluid.

FIGS. 17 and 19 illustrate methodologies to facilitate analysis,diagnosis and maintenance of lubricating fluids in accordance with thepresent invention. While, for purposes of simplicity of explanation, themethodologies are shown and described as a series of acts, it is to beunderstood and appreciated that the present invention is not limited bythe order of acts, as some acts may, in accordance with the presentinvention, occur in different orders and/or concurrently with other actsfrom that shown and described herein. For example, those skilled in theart will understand and appreciate that a methodology couldalternatively be represented as a series of interrelated states orevents, such as in a state diagram. Moreover, not all illustrated actsmay be required to implement a methodology in accordance with thepresent invention.

FIG. 17 is a flow diagram of a sensor data and quality collection andreporting process 400 according to an aspect of the present invention.Since multiple sensing components can be employed as described abovealong with sensor fusion data, useful information regarding the qualityand accuracy of data associated with the fluid can be provided. Forexample, data quality metrics can be readily incorporated into andreported by the control module 310 described above. Proceeding to 410,quality parameters are determined for a fluid. The quality parameters ofa lube analysis, for example, can be based on and change according tothe time since the last calibration, the degradation of sensorcomponents such as from age, and according to a failure of a sensorcomponent. For example, if a sensor calibration is due or past due, aquality estimate for that parameter can be lowered (e.g., probability orpercentage that sensor reliability is less when further away in timefrom calibration).

At 420, sensor data is acquired (e.g., processor reading fluid sensorcomponent and storing data related thereto). At 430, a quality estimateis computed for the associated sensor based upon the criteria orparameters established at 410. At 440, sensor data is reported alongwith the associated quality estimate. In this manner, an engineer orsystem can make more accurate determinations regarding the fluid data asreported by the sensor since reliability of the data is also reportedvia the associated quality estimate. In this manner, rather than justreport an incorrect value, a control module can provide the measuredvalue along with the quality estimate. Alternatively, the control modulecan provide a corrected sensor value based on historical data, sensorand fluid physics, and/or sensor fusion. Additionally, the controlmodule can provide a “raw”—as read from sensor value, a corrected value,and confidence limits and/or a belief value for the reported sensordata.

FIG. 18 illustrates a closed-loop system 500 to adjust fluidcharacteristics according to an aspect of the present invention. In thisaspect of the present invention, fluid lifetime can be extended via oneor more excitation stimuli operative with a fluid 506, such as anequipment lubricant, in order to alter properties of the fluid. Thestimuli can be provided via a control module 510 that includes a powersource 512, wherein a processing and memory unit 530 is operative toprovide control aspects to the module 510 as described below.

Oxidation present in greases and oils can be determined by employingcyclic volta-metric techniques. A multi-electrode component 534 isillustrated including a working electrode, reference electrode, and acounter electrode. It is noted that other combinations or numbers ofelectrodes can be employed to perform the measurements. For example, atwo-electrode system can be utilized to perform cyclic volta-metrictechniques. By applying a voltage (V) across the working and referenceelectrode, a current (I) can be induced in the counter electrode inorder to determine such parameters as oxidation in the fluid 506.

The voltage can be cyclically ramped up and down from −5V to +5V to −5Vto +5V to −5V, for example, and the current recorded during the voltageexcursions. Characteristic peaks observed and analyzed in an I-V curvecan be driven by an oxidation and reduction that occurs in the fluid 506in substantially close proximity to the component electrodes 534. Theoxidation reaction is typically not the addition of oxygen to compoundsin the fluid 506 but rather the loss of electrons in the compounds.Similarly, a reduction phase of the operation results in a gain ofelectrons for fluid compounds.

In addition to sensing when the oxidation and reduction has occurred inthe fluid 506, the control module 510 can provide an excitation signalvia the electrodes 534 to mitigate degenerative aspects of the fluid 506such as from oxidation—thus, providing loop closure to sense the healthand then facilitate restoration of the fluid 506. The excitation signalcan be generated for a longer time period and higher voltage(longer/higher—relative to oxidation detection cycles described above)for a reduction phase and followed with a brief, low voltage excitationfor a complete reduction cycle. Additional voltage and time spent in thereduction phase is employed to reduce the oxidation present in the fluidcompounds such as antioxidants.

Other type electrodes 534 can be fabricated on the control module 510 toprovide a larger surface area and support a higher power output for thereduction reaction. It is to be appreciated that an array of suchreducing electrodes 534 can be constructed and alternatively, selectedportions of the array can be activated if degradation or wear ofelectrodes occur during the reducing cycle.

Another aspect of the present invention includes fabrication ofmicro-electronic magnetic structures 540 along with micro-electronicsensors or detectors 544 on the control module 510. The magneticstructures 540 facilitate attracting ferrous metallic particles from thefluid 506, wherein presence of a magnetic field will prevent theseparticles from flowing freely in the fluid and migrating into rollingelements and associated equipment contact surfaces. A larger structure540, perhaps outside the path of rolling elements, can serve to mitigatehaving such metal particles contaminate a raceway, for example. Suchattracted materials can also be bound to a sensor electrode via aplating-type operation. The amount of ferrous materials attracted can bemeasured with any of a number of detectors 544 which includeconductivity between several sensor electrodes, plating energy, orcapacitive or dielectric strength between several surfaces. It is to beappreciated that oxidation and particle removal aspects of the presentinvention do not have to be combined into a singular control module butcan also be provided as part of separate control module or function.

FIG. 19 is a flow diagram of a lubrication control process 600 accordingto an aspect of the present invention. This process can be executed bythe control modules described above and/or can be implemented accordingto a control state machine and/or algorithm, for example. Proceeding to610, an excitation signal is applied to a fluid in order to change oralter the characteristics or performance of the fluid. For example, avoltage can be applied in the form of an extended pulse and/or increasedvoltage magnitude in order to replenish electrons that have beendepleted from the fluid. In another aspect, a magnetic field can beapplied as the excitation signal in order to remove contaminants such asferrous material from the fluid. It is noted that the excitation pulsecan also be directed to an actuator or controllable valve, whereinadditives are provided to the existing fluid as described above. At 620,fluid parameters are measured in order to determine the effectiveness ofthe excitation signal applied at 610. For example, current can bemeasured when applying voltage pulses to determine an amount ofoxidation present in the fluid. In the case of ferrous particles,conductivity can be measured between electrodes, measured via platingenergy, and/or measured between capacitive surfaces, for example.

At 630, a determination is made whether the fluid measurements of 620are in range. This can include setting predetermined parameterthresholds and making the determination regarding the fluid based uponthe measured parameter being above or below the predetermined threshold.If the measured fluid parameter is in range at 630, the process proceedsto 640 and removes the excitation signal from the fluid or in the caseof additives, a valve can be disengaged. If the measured parameter isout of range at 640, the process proceeds back to 620 and performsanother fluid measurement. It is noted, that the loop depicted between620 and 630 can be executed as a background routine, wherein a processorperiodically returns, performs the measurement at 620 and makes thedetermination at 630. In addition, a counter can be set whereby if themeasurements taken at 620 are not within range after a predeterminednumber of readings as indicated by the counter, a control signal can beactivated and/or alarm triggered that the fluid is not responding to theexcitation signal applied at 610.

What has been described above are preferred aspects of the presentinvention. It is, of course, not possible to describe every conceivablecombination of components or methodologies for purposes of describingthe present invention, but one of ordinary skill in the art willrecognize that many further combinations and permutations of the presentinvention are possible. Accordingly, the present invention is intendedto embrace all such alterations, modifications and variations that fallwithin the spirit and scope of the appended claims.

1. A system that analyzes health of a lubricant in a machine,comprising: a component that senses, in situ, a characteristic of thelubricant; an analyzer that compares the sensed characteristic of thelubricant with a pre-defined characteristic of the lubricant, whereinthe result of the comparison is utilized to determine lubricant health;and the analyzer further compares the determined lubricant health withknown acceptable parameters and a projected lubricant aging in order toestablish a recommended maintenance action and determine when thismaintenance must be performed.
 2. The system of claim 1, the componentis a pH sensor that determines an ionic condition of the sensedlubricant.
 3. The system of claim 1, the component is a chemical sensorthat determines presence of a chemical contaminant of the lubricant. 4.The system of claim 1, the component is a conductivity sensor todetermine presence of at least one of a metal contaminant and a watercontaminant of the lubricant.
 5. The system of claim 1, the component isa sensor that measures temperature for determining lubricant viscosity.6. The system of claim 1, further comprising a diagnostic component thatdynamically controls a qualitative and/or quantitative aspects of thelubricant based at least in part on the health of the lubricant toreduce at least one of lubricant degradation, depletion and oxidation.7. The system of claim 1, the lubricant is one of a hydraulic fluid, anoil, and a grease.
 8. The system of claim 1, the component furtherconverts the sensed characteristic into a form readable by the analyzer.9. A system for maintaining the health of a lubricant of a machine,comprising: means for sensing a real-time lubricant property; means fordetermining health of the lubricant from the sensed lubricant property;means for comparing the determined lubricant health with knownacceptable parameters and a projected lubricant aging; means forestablishing a recommended maintenance action; and means for determiningwhen the maintenance must be performed based on the lubricant healthdata.